My friend has a 2003 Pontiac Vibe, automatic transmission, front wheel drive, with 50,000 miles. For the past week or so we have noticed a loud rattling noise upon acceleration, in both drive and reverse. It only does it when we first start to accelerate. Once we get going it stops. Its really hard to tell where the noise is coming from most of the time it sounds like it is coming from the front of the car but every once in a while it sounds like its coming from the rear. Does anyone have any idea what could cause this? Thanks for any and all advise!!